# How do electrons keep out of the nucleus?

1. Mar 9, 2005

### penguinraider

Apart from inertia and a nucleus' "gravity" (I invisage it's like the planets revolving around the sun), are there any other factors that keep the electrons from being attracted to the protons and crushing into the nucleus?

2. Mar 9, 2005

### dextercioby

Gravity doesn't contribute with (almost) nothing.It can be totally neglected.The model with planets orbitting the Sun it's good for planets orbitting the Sun,it's perfectly useless (due to incorrectness) in atomic description.

The laws of Quantum Mechanics (its axioms & results) applied to the atom give all the proof needed for atomic stability.

Daniel.

3. Mar 9, 2005

### Staff: Mentor

I suggest you check it out and post any further questions there.

[Argh, Daniel must be able to type faster than I can!]

4. Mar 10, 2005

### marlon

Here is how you should look at the fact that electrons do not crash onto the atomic nucleus and why they don't radiate : there is no radiation of electrons in an atom. The electrons move indeed in orbitals with a certain velocity (no acceleration). Now the fact that electrons do not fall into the nucleus due to the Coulombic interaction has to do with the fact that there is an equilibrium in both potential and kinetic energy.

Electrons that are "closest" to the nucleus have a lower potential energy (more negative) but they move in the orbitals with higher speed (higher kinetic energy). Once you look at electrons further waway from the nucleus, the potential energy rises and the velocity (and therefore the kinetic energy) lowers. In the end there is an equilibrium between those two.

marlon

5. Mar 16, 2005

### Antiphon

We should be careful. Accelerating a charge is not enough to produce
radiation. If it were, then electrons at rest in a gravity field would radiate since they are being constantly accelerated.

Furthermore, atomic quantum orbitals are anything but constant velocity
configurations, since a change in either direction or speed implies acceleration.

A better answer is needed for why electrons don't radiate in atomic orbitals,
and it is a purely quantum mechanical explanation (which I myself am still looking for.)

6. Mar 16, 2005

### ZapperZ

Staff Emeritus
Well, since we are trying to "be careful" here, let's also make sure we be extra careful in saying that the atomic orbitals somehow implies a "velocity" or speed of anything. It doesn't. By saying such things, we are already implicitly implying a well-defined charged particle moving around. You don't have such things until a position measurement is done. Before then, an electron in an s-orbital, for example, has no well-defined position and identity. Rather, based on the wavefunction alone, it is "spread out" in a uniform sphere around the nucleus. So the electron is everywhere simultaneously (which is connected to the Schrodinger Cat-type puzzlement - another illustration that things in QM are interconnected). This is how we get an angular momentum of zero for the s-orbital - from the geometry of the orbital itself.

This is another illustration where our social language can cause many confusion in trying to describe things that have no linguistic equivalent. As soon as we say "electron moves in an orbit", a whole range of implications kick in. We automatically imply that there is this well-defined object that we can track along the way and moving in a well-defined trajectory. QM implies no such thing, at least as far as atomic orbitals are concerned. We have seen a whole zoo of evidence where an "electron" can simultaneously spread itself into many locations to produce unclassical effects (bonding-antibonding bands, etc.) .

Zz.

7. Mar 16, 2005

### marlon

Well, indeed maybe i shoudn't have written constant velocity...That is indeed not correct. But the point really is the equilibrium between potential and kinetic energy.

marlon

8. Mar 29, 2005

### nebulan

elctric feild is the answer....the protons are positive
the elctron are negative
if the elctron were putted in a right place and shooted in a right velocity it will orbit the proton and never hitting it
..by the way

its a bad example saying that the atomic structure are like planets

its not right to say that the elctrons orbiting the nucleas is like planets revolving around the sun

the elctron was thoght a partical but sceintests discoverd that it is a wave

its true

qm quantum meachanicks is filled with uncorrect statics

but it helped a lot for understanding the atomic srtucture

9. Mar 29, 2005

### dextercioby

I think those are false claims...If u have a source to document your affirmation,please,post them and i'll accept it/them.

Till then,please,do not post erroneous claims...

Daniel.

P.S.It would help your cause a lot,by spelling English properly.We have a spell checker,in case u haven't noticed...

10. Mar 29, 2005

### nebulan

Last edited by a moderator: Apr 21, 2017
11. Mar 29, 2005

### dextercioby

1.Electron is not a wave.
2.Quantum Mechanics "is filled" with correct descriptions of nature.

There's a giant thread in the QM & QFT forum about "What's wrong with QM?".Maybe you'd like to share your views with us.Who knows,we might learn something...

Waiting you there,

Daniel (sic!).

P.S.Good thing it's not "denial" :surprised:

12. Mar 29, 2005

### inha

Last edited by a moderator: Apr 21, 2017
13. Mar 29, 2005

### Ba

How does a wave have a spin? I know an electron does.

14. Mar 29, 2005

### nebulan

its wave are collided to a ball shape
A physicist named Erwin Schrödinger showed that electrons are really waves
check this scientest Erwin Schrödinger and youl know that an elctron is a wave

15. Mar 29, 2005

### dextercioby

The classical equivalent of photon spin is what we call independent polarization directions of an em wave.Incidentally,in QFT,when describing a photon,we use the wording "polarization states" when talking about helicity eigenstates of the photon...

Daniel.

16. Mar 29, 2005

### inha

wow. how did you reach this conclusion from schrödinger's formulation of quantum mechanics?

17. Mar 29, 2005

### dextercioby

A correct description of the concept of "electron" is offered by the quantum theory of the Dirac field.Period.

Daniel;

18. Apr 14, 2005

### Dragongod

the problem is no field of science has ever explicitly stated whether or not and showed logically how, a field is not made up of mass, matter. To say a field can exist in of itself is to say that energy can exist without mass. Its also to imply that F=ma is wrong, as well as, E=mc^2 because both these formulas indicate that a field must actually be comprised of particles (mass, matter) - that energy and mass cannot exist without each other.

19. Apr 14, 2005

### marlon

I really wonder where people keep getting the idea that an electron is a field. Especially in QFT ???

marlon

20. Apr 14, 2005

### dextercioby

The electron is a quanta of the electron field:a Grassmann $\left(\frac{1}{2},0\right)\oplus \left(0,\frac{1}{2}\right)$ irreductible representation of $\mbox{SO(3,1)}$ to which certain conditions are imposed (see the solving of Dirac's equation for free field).

Daniel.